The present invention pertains generally to organic synthesis and in particular to a rapid synthesis of a diether-linked polyphthalonitrile resin.
A major advantage of phthalonitrile resins compared to other plastics is their ability to withstand temperature in excess of 200.degree. C. for extended periods without permanent damage to the coatings, plastics or composites made therefrom. Presently, epoxies and polyimides are being used but each has its disadvantages. Conventional epoxy-based composites and adhesives are limited to 120.degree. C. maximum service. Other problems associated with these polymers include their brittleness, water absorptivity and engineering reliability.
Certain phthalonitrile resins are proving to be superior in physical and chemical properties to epoxies, polyimides and other plastics as matrices for fiber-reinforced composites. It is necessary for a resin not to produce gaseous products when cured. Also the chemical make-up of the polymer must be such that it consists of units having known resistance to bond-rupture under thermal, oxidative, and hydrolytic conditions.
Such resins usually contain a substantial proportion of aromatic structures but cured polymers composed solely of aromatic rings tend to be brittle and intractable. If a resin has flexible linkages between the aromatic rings, these disadvantages would be minimized or eliminated. Polyphthalocyanines with diether linkages are materials which meet these goals. Examples of these polyphthalocyanines are found in U.S. Pat. Nos. 4,223,123; 4,226,801; 4,234,712; 4,238,601 by T. M. Keller and J. R. Griffith. However, these monomers are extremely slow to polymerize and cure, generally taking several days and requiring extremely high temperatures.